Press for amalgams and the like



P 1962 R. HARVEY 3,052,985

PRESS FOR AMALGAMS AND THE LIKE Filed NOV. 7, 1960 aired Statesinvention relates to presses for extracting liquids from substances.

The initial embodiment of the invention is a miniature press to be usedby dentists for removing excess mercury from silver amalgam. Thedescription of this initial embodiment will provide adequate guidancefor those skilled in the art who may have occasion to construct such apress for other specific purposes.

The consistency of silver amalgam depends on the proportions of mercuryand silver, and may be varied simply by subjecting the amalgam topressure for extraction of a portion of the mercury. In the usualprocedure, a dentist requires a particular consistency for the initialdeposit of amalgam in a cavity of a tooth and requires progressivelydrier increments of amalgam to complete the filling.

A common practice is to use an amalgam press of the constructiondisclosed in my prior Patent 2,795,850. Such a press consistsessentially of two relatively rotatable parts, namely, a base assemblyto be held in one hand and a screw means for operation by the otherhand. The base assembly provides a cavity to receive a quantity ofamalgam and includes means with a threaded bore to engage the screwmeans for advance against the amalgam. The dentist takes a portion of arelatively wet body of amalgam for starting a filling, and uses thepress to extract successive amounts of mercury from the body of amalgamto produce the progressively drier increments to complete the filling.

The problem is to operate such hand press in such manner as to produce abody of amalgam to a desired consistency. With practice, a dentistdevelops a certain feel for guidance in the operation of such a handpress that enables him to approximate a desired result. Accuracy islacking, however, and too often the procedure is a time wasting, trialand error procedure.

For efliciency, a dentist should have an assistant to process theamalgam. Here the further problem arises of teaching an assistant to beproficient in handling the press and of communicating to the assistantthe particular consistencies required for the amalgam at differentpoints in the procedure of fiiling a tooth. An assistant may becomecompetent in the required teamwork, but the training and practice muststart over again if the assistant is replaced by a new assistant.

The present invention meets this problem by adding a third relativelymovable part to the two relatively movable parts of a press such asdescribed above, with a suitable spring acting between the third partand one of the other two parts. In the first practice or" the inventiondescribed hereafter, the third part is a holder which rotatably seatsthe base assembly. Spring means resists relative rotation between theholder and the base assembly in the direction that rotation tends tooccur in reaction to the resistance that is encountered by the screwmeans.

With a quantity of amalgam in the press, the operator takes the holderin one hand and turns the screw means with the other hand. Until thescrew means reaches pressure contact with the confined amalgam, thespring means prevents relative rotation between the holder and the baseassembly so that the base assembly initially functions in efiect as anintegral part of the base assembly. After the screw means makes pressurecontact with the confined amalgam, however, resistance to advance of thescrew means rises progressively with consequent progresi cc 2 siveyielding of the spring means to permit corresponding rotation of thebase assembly relative to the holder. The yielding action of the springmeans with the consequent relative rotation between the holder and thebase assembly is a measure of the pressure to which the amalgam issubjected.

The yielding action of the spring is readily sensed by the operator. Theoperator detects the point at which the yielding action is initiated andcan then sense the extent to which the spring yields as the rotation ofthe screw means is continued. Thus the improved press provides means forthe operator to develop a more reliable feel for guidance in processingamalgam.

The preferred practice of the invention includes index m ans to measurethe relative rotation between the holder and the base assembly, whichrelative rotation measures the extent to which the spring means yieldsand thus measures the rise in pressure applied to the amalgam. Byemploying an index means in the form of a graduated scale with anindicator movable along the scale, the invention makes it possible toapply accurately selected degrees of pressure, and thus makes itpossible to process amalgam accurately to any desired degree of dryness.There is no problem in training an assistant in the use of the press andno problem in communication, because the dentist can express hisrequirements accurately in terms of scale values.

In a second practice of the invention, the third relatively rotatablepart is added to the screw means, not the base assembly, and comprises ahandle with suitable spring means resisting rotation between the handleand screw means. The operator holds the base assembly in one hand androtates the handle with the other hand. The mode of operation is thesame.

The features and advantages of this invention may be understood from thefollowing detailed description and the accompanying drawing.

In the drawing, which is to be regarded as merely illustrative:

FIG. 1 is a sectional view of a selected embodiment of the inventionwith the screw means positioned for advance against a quantity ofamalgam in the cavity of the base assembly;

FIG. 2 is a side elevation with parts broken away showing the screwmeans advanced into pressure contact with the amalgam in the cavity;

FIG. 3 is a transverse section taken as indicated by the line 3-3 ofFIG. 1 showing the spring means in unstressed state;

FIG. 4 is a plan view of the press with parts broken away showing thespring means stressed for the application of a particular magnitude ofpressure, and showing the pointer and scale for indicating the magnitudeof the pressure;

FIG. 5 is a fragmentary section taken as indicated by the line 55 ofFIG. 4 showing how a pin extends from the base assembly into an arcuategroove of the holder to act against one of the two springs thatconstitute the spring means;

FIG. 6 is a side elevation, partly in section, showing the secondembodiment of the invention in which the third relatively rotatable partis a handle for the screw means;

FIG. 7 is a transverse section as indicated by the line 77 of FIG. 6showing the two springs in their normal confi urations; and

FIG. 8 is a plan view as seen along the line 88 of FIG. 6 showing theindex means for indicating the various degrees of pressure applied tothe amalgam.

In the first embodiment of the invention shown in FIGS. 1-4, the baseassembly comprises a circular metal base block 10 with a cylindricalcavity 12, and a yoke 14 that is attached to the base block and has ascrew threaded bore for axial alignment with the cylindrical cavity. Thescrew means for cooperation with the base assembly comprises a screwmember 16 for mounting in the threaded bore 15. One end of the screwmember 16 forms a cylindrical ram 18 for snug, sliding fit in thecylindrical cavity 12. The second outer end of the screw member 16 has aknob 20 for manual operation, the knob being fixedly secured to thescrew member by a suitable setscrew 22.

The base block 10, which is formed with a cylindrical boss 24 on itslower side, has an axial bore 25. An ejector member 26 which normallyrests on the bottom of the cylindrical cavity 12 has an axial stem 28that is slidingly mounted in the bore 25. The ejector member fitssufiiciently loosely in the cylindrical cavity 12 and the axial stemseats sufficiently loosely in the axial bore to permit drainage of themercury that is squeezed out of the amalgam in the cylindrical cavity12. The lower end of the stem 28 is provided with a knob 30 for manualoperation and this knob serves as stop means to limit the upwardmovement of the ejector member 26. Preferably, the upper limit positionof the ejector member 26 is substantially flush with the upper surfaceof the base block 10.

One of the two arms of the yoke 14 is formed with a bore 32 by means ofwhich the yoke is journaled on a stud 34 to swing laterally between theposition shown in solid lines in FIG. 1 and an alternate position shownin dotted lines. 'The stud 34 is formed with a head 35 to retain theyoke and is mounted in a threaded bore 36 in the base block 10. Thesecond arm of the yoke 14 is formed with a hook 38 for releasableengagement with a second stud 40. The second stud has a head 42 forabutment by the book 38 and is mounted in a threaded bore 44 at the baseblock 10. With the ram 18 at the end of the screw member 16 retractedfrom the cylindrical cavity 12, the yoke 14 may be swung to the dottedline position in FIG. 1 to make the cylindrical cavity 12 accessibleeither for introducing a quantity of wet amalgam into the cavity or forremoving processed amalgam from the cavity.

The circular base block 10 is rotatably mounted in a circular seat 45 ina suitable holder 46 that is dimensioned to be held in the palm of onehand. In this embodiment of the invention the holder 46 is a solid blockof metal of generally circular configuration, with a pair ofdiametrically opposite tapered wings 48 to permit the holder to begripped in a manner to prevent rotation of the holder in the operatorshand.

Any suitable arrangement may be used to retain the base block in thecircular seat. In the construction shown, the holder 46 has a relativelylarge axial bore 50 extending from the circular seat 45 to the undersideof the holder, this bore being dimensioned to receive the boss 24 on theunderside of the base block 10. A retainer bushing 52 is seated in theaxial bore 50 with a radial flange 54 of the bushing abutting the bottomsurface of the holder. The retainer bushing 52 surrounds the axial stem28 of the ejector member 26 and is releasably connected to the baseblock 10 by a pair of screws 55. The knob or handle 30 of the ejectormember 16 abuts the retainer bushing 52 at the upper limit position ofthe ejector member 16.

Any suitable spring arrangement may be provided for the requiredyielding resistance to relative rotation between the base block 10 andthe holder 46. In this particular embodiment of the invention, thecircular seat 45 in the holder 46 is provided at its bottom with a pairof diametrically opposite arcuate slots 56 as shown in FIGS.

3 and 5 to seat a pair of corresponding coiled springs 58.

The base block 10 is provided with a pair of corresponding downwardlyextending pins 60 that extend into the arcuate slots 56' in abutmentwith the ends of the corresponding coiled springs 58.

These springs 58 resist the relative rotation between the base block 10and the holder 46 that tends to occur in reaction to resistanceencountered by the ram 18. The

4- two springs are strong enough to overcome the normal frictionalresistance to rotation of the screw member 16 that occurs in the screwthreaded bore 15 of the yoke 14 so that the two springs yield only whenthe ram 18 makes pressure contact with a quantity of amalgam in thecylindrical cavity 12.

In this particular embodiment of the invention, a suitable index meansis provided to indicate the magnitude of relative rotation between thebase block 10 and the holder 46, thereby to indicate the correspondingcompression of the two coiled springs 58 and the corresponding magnitudeof pressure that is exerted by the ram 18 against the amalgam in thecylindrical cavity 12 Such an index means may comprise an index mark 62on the holder 46 to serve as a pointer or indicator to traverse a scale'64 on the base block 10. In this instance, the scale shows a series ofarbitrary values numbered 1 to 5.

The manner in which the described press functions for its purpose may bereadily understood from the foregoing description. With the ejectormember 16 at its normal position in the bottom of the cylindrical cavity12 and with the screw member 16 retracted and the yoke 14 swung to oneside, as shown in dotted lines in FIG. 1, the cylindrical cavity 12 inthe base block 10 is exposed to receive a small body 65 of wet amalgam,i.e., silver amalgam with a high content of mercury.

The yoke 14 is then swung to its operative position shown in FIG. 1 withthe hook 38 on the swinging end of the yoke in abutment with the head 42of the stud 40. The operator then grips the holder 46 in the palm of onehand and rotates the knob 29 to advance the cylindrical ram 18 by screwaction.

Until the cylindrical ram 18 makes pressure contact with the amalgambody 65 in the cylindrical cavity 12, no relative rotation occursbetween the base block 10 and the holder, the holder functioning ineffect as an integral portion of the base block. When the cylindricalram 18 makes pressure contact with the amalgam body 65, continuedrotation of the screw member 16 relative to the base assembly results ina rise in the resistance to advance of the ram and this risingresistance results in corresponding relative rotation between the baseblock and the holder against the resistance of the pair of coiledsprings 58. The index mark 62 is correspondingly advanced along thescale 64.

By always starting with an amalgam body 65 of a given wetness or mercurycontent, the operator is assured that the amalgam body is reduced inmercury content to a given degree each time the index marker 62 reachesa given value on the scale 64. Thus, the scale numerals accuratelyrepresent corresponding predetermined, progressive degrees of dryness ofthe amalgam body.

Once the dentist has standardized this procedure, starting with amalgamof a given mercury content, he may readily carry out the operation toproduce successive increments of amalgam with predetermined changes inmercury content. It requires no skill whatsoever for an assistant tomanipulate the press for the same accurate results. It is a simplematter for a dentist to guide an assistant in the operation of thedevice by merely referring 'to selected values on the scale 64.

The second embodiment of the invention, shown in FIGS. 6, 7 and 8,operates in the same general manner as the first embodiment of theinvention but in this instance the third relatively rotatable part isassociated with the screw member 16 instead of being associated with thebase assembly.

In the second embodiment of the invention the base block 10a is largeenough to be conveniently gripped in the palm of the hand and is of thesame general shape as the previously described holder 46. Thus, the baseblock 10a is formed with a pair of diametrically opposite tapered wings65 to permit the holder to be gripped against rotation. The base block10a has the usual cylindrical cavity 12a and is equipped with the usualejector member 28a, having the usual axial stem 23:: and knob 30a.

A yoke 14a of the prefiously described construction is mounted in theusual manner on a stud 34a for swinging movement into and out of hookengagement with a second stud 40a. The screw member 16a is of thepreviously described construction, with a cylindrical ram portion 18a onits leading end. A circular knob 68 is fixedly mounted on the screwmember 16a and is anchored against rotation thereon by a suitablesetscrew 70.

A handle 75 in the form of a cap is rotatably mounted on the screwmember 16a and is formed with a cylindrical skirt that rotatablysurrounds the circular knob 68. The upper or outer end of the screwmember 160 is formed with a radial flange 78 to retain the rotary handle75 against axial separation from the circular knob 68.

The means to resist rotation of the handle 75 relative to the circularknob 68 may comprise a pair of coiled springs 80 seated in acorresponding pair of arcuate slots 82 in the circular knob 63. In thepreviously described manner, a pair of pins 84 extend downward from thehandle 75 into the arcuate slots 82 for abutment against the ends of thecorresponding coiled springs 8%. A suitable index-means for indicatingdegrees of relative rotation between the handle 75 and the circular knob68 may comprise a pointer 85 formed on the radial flange 78 of the screwmember 16a to traverse a cooperating scale 86 on the upper surface ofthe handle 75.

It is apparent that the second embodiment of the invention functions inthe same basic manner as the first embodiment.

My description in specific detail of the selected embodiments of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure, within the spirit and scope of theappended claims.

I claim:

1. In a press for squeezing a quantity of a substance, the combinationof: a first means providing a cavity to receive said substance andproviding a screw-threaded bore in axial alignment with the cavity; asecond means having a ram portion to enter the cavity and a screwportion in threaded engagement with said bore to advance the ram; amember rotatably connected to one of said two means for rotationrelative thereto coaxially thereof, said member having a normal rotaryposition relative to said one of the two means; and spring means actingbetween said member and said one of the two means to oppose relativerotation between the member and said one of the two means in reaction toresistance to advance of the ram against the substance in the cavity,whereby said member and the other of the two means may be rotatedrelative to each other to advance the ram against the substance in thecavity until the substance is subjected to a predetermined pressure asindicated by yielding of the spring means and by corresponding relativerotation between the member and said one of the two means.

2. In a press for subjecting a substance to pressure of a predeterminedmagnitude, the combination of: a first means providing a cavity toreceive said substance and providing a screw-threaded bore in alignmentwith the cavity; a second means having a ram portion to enter the cavityand a screw portion in threaded engagement with said bore to advance theram; a member rotatably connected to one of said two means for rotationrelative thereto coaxially thereof, said member having a normal rotaryposition relative to said one of the two means; spring means interposedbetween said member and said one of the two means to yieldingly resistrelative rotation of said member out of its normal position in reactionto resistance to the advance of the ram; and cooperative index means onsaid member and on said one of the two means to indicate the extent towhich said member rotates relative to said one of the two means whensaid ram is advanced against resistance, whereby said member and theother of the two means may be rotated relative to each other to advancethe ram against the substance in the cavity until said spring meansyields to a predetermined degree to place the substance underpredetermined pressure as indicated by said index means.

3. A combination as set forth in claim 2 in which said member isrotatable relative to said first means, and said spring means isinterposed between said member and said first means.

4. A combination as set forth in claim 2 in which said member isrotatable relative to said second means, and said spring means isinterposed between said member and said second means.

5. A combination as set forth in claim 2 in which said index meanscomprises a scale and a cooperative indicator.

6. In a press for removing excess mercury from silver amalgam for dentaluse, the combination or: a base assembly providing a cavity to receivethe amalgam and providing a screw-threaded bore in axial alignment withthe cavity; a manually operable screw means in threaded engagement withsaid bore to exert pressure on amalgam in the cavity; a holder for thebase assembly rotatably mounted thereon to be gripped manually foroperation of the press; spring means interposed between the baseassembly and the holder to oppose relative rotation be tween the baseassembly and the holder in reaction to resistance to advance of thescrew means against the amalgam in the cavity, whereby said screw meansand said holder may be rotated relative to each other to advance thescrew means against the amalgam in the cavity until the amalgam issubjected to a predetermined pressure as indicated by yielding of thespring means and corresponding relative rotation between the holder andthe base assembly.

7. In a press for removing excess mercury from silver amalgam for dentaluse, the combination of: a base assembly providing a cavity to receivethe amalgam and providing a screw-threaded bore in axial alignment withthe cavity; a manually operable screw means in threaded engagement withsaid bore to exert pressure on amalgam in the cavity; a holder for thebase assembly rotatably mounted thereon to be gripped manually foroperation of the press; spring means interposed between the baseassembly and the holder to oppose relative rotation between the baseassembly and the holder in reaction to resistance to advance of thescrew means against the amaL gain in the cavity; cooperative index meanson said holder and base assembly to indicate the extent to which theyholder rotates relative to the base assembly when the screw means isadvanced against the resistance of the amalgam in the cavity, wherebythe holder and the screw means may be rotated relative to each other toadvance the screw means against the amalgam in the cavity until thespring means yields to predetermined degree to place the amalgam underpredetermined pressure as indicated by the index means.

8. A combination as set forth in claim 7 in which said index meanscomprises a scale and a cooperative indicator.

9. A combination as set forth in claim 7 in which one of said holder andbase assembly has an arcuate concentric slot with said spring meanstherein and the other of said holder and base assembly has a portionextending into said slot to stress the spring means in response torelative rotation between the holder and the base assembly.

10. In a press for removing excess mercury from silver amalgam fordental use, the combination of: a base assembly providing a cavity toreceive the amalgam and providing a screw-threaded bore in axialalignment with the cavity; screw means in threaded engagement with saidbore to exert pressure on amalgam in the cavity; a handle rotatablymounted on said screw means; and spring means interposed between theholder and the screw means to oppose relative rotation between thehandle and h the screw means in reaction to resistance to advance of thescrew means against the amalgam in the cavity, whereby said handle andsaid base assembly may be rotated relative to each other to advance thescrew means against the amalgam in the cavity until the amalgam issubjected to a predetermined pressure as indicated by yielding of thespring means and by corresponding relative rotation between the handleand the screw assembly.

11. A combination as set forth in claim 10 which includes coopenatingindex means on said handle and said screw means to indicate relativerotation between the handle and the screw means thereby to indicate themagnitude of the pressure exerted by the screw means against the amalgamin the cavity.

12. In a press for removing excess mercury from silver amalgam fordental use, the combination of: a base assembly providing a cavity toreceive the amalgam and providing a screw-threaded bore in axialalignment with the cavity; screw means in threaded engagement with saidbore to exert pressure on amalgam in the cavity; a handle rotatablymounted on said screw means; an arouate concentric slot in one of saidhandle and screw means; a coiled spring in said slot; and meansextending into said slot from the other of said handle and screw meansto compress said spring in response to relative rotation between thehandle and the screw means, whereby said base assembly and said handlemay be rotated relative to each other to advance the screw means againstamalgam in the cavity until the amalgam is subjected to a predeterminedpressure as indicated by yielding of the spring means and correspondingrelative rotation between the handle and the base assembly.

References Cited in the file of this patent UNITED STATES PATENTS2,157,574 Siesel May 9, 1939 2,651,110 Dike Sept. 8, 1953 2,795,850Harvey June 18, 1957

